1. Field of the Invention
The present invention relates to the field of photography and, more particularly, to photographic systems, apparatus, and components for handling and processing large format self-developing film units.
2. Description of the Prior Art
The introduction of professional quality 8.times.10 color self-developing film units for use by professional photographers in the advertising and graphic arts industry has greatly increased the demand for more simplified and efficient film processing equipment.
In a typical commercial photography application, using presently available film and processing apparatus, a discrete photosensitive or negative sheet element, provided in a light opaque protective bag, is loaded into a holding cassette and then the protective bag is withdrawn through a film withdrawal slot at the leading end of the cassette. Then the cassette is inserted into a cassette holder on the back of a commercially available 8.times.10 view camera, a dark slide covering the cassette exposure aperture is pulled out, and the photosensitive sheet is exposed. The dark slide is then returned to its blocking position and the cassette is removed from the camera for transfer to a processing apparatus.
For an example of a commercially available large format processor, cassette, and self-developing film unit, reference may be had to U.S. Pat. No. 4,019,194 issued on Apr. 19, 1977 to Norman W. Cutler, Jr. et al. and being assigned to the same assignee as the present invention.
As indicated in the above patent, the photosensitive sheet element includes a leader attached to its forward end having sheet coupling structure thereon including a shoulder portion and a forwardly extending relatively narrow coupling tab. The companion image-receiving sheet includes a leader mounting a rupturable container of fluid processing composition and having a leader portion with a tab receiving slot therein and shoulder bearing portions adjacent the slot.
When the photosensitive sheet element is loaded into the cassette and the protective bag is removed, the leader tab thereof extends out through the withdrawal slot and is folded over and releasably coupled to the back of the cassette before the exposure phase. Following exposure, the image-receiving sheet is inserted into the cassette in superposed relation to the photosensitive sheet element. At this point, the user detaches the tab from the back of the cassette and inserts it through the tab receiving slot of the image-receiving sheet to operatively couple the positive and negative sheets together in cassete face-to-face registration. The cassette is then transferred to the processing apparatus which has an entry slot for receiving the forward end of the cassette. When the cassette is so inserted, the protruding tab is fed into the bite of a pair of processing rollers which are driven by an electrical motor. The rollers advance the coupled positive and negative sheet elements therebetween while applying a compressive pressure progressively along the length of the film unit to discharge the fluid processing composition from its container and distribute the fluid between the superposed sheet elements. Following a short imbibition period, the positive and negative sheet elements are stripped apart to reveal the positive reflection print on the image-receiving sheet.
While this system produces excellent results, it is rather inefficient and time consuming because of the number of manual film manipulation steps involved. For each photograph, the photographer must load the negative sheet element into the cassette, withdraw the protective bag, fold the coupling tab over the back of the cassette and attach it to a receiving post, load the image-receiving sheet into the cassette following exposure, detach the coupling tab from the cassette, and finally thread the tab through the receiving slot of the image-receiving sheet to couple the positive and negative sheet elements together.
An improved and more efficient version of the above described system is disclosed in commonly assigned copending applications U.S. Ser. Nos. 841,888 and 841,889 both being filed on Oct. 13, 1977 by Herman E. Erikson. In this system, the image-receiving sheet element is placed in a tray on the processor. When the cassette holding the negative sheet element is inserted into a tray, the protruding coupling tab is automatically inserted through the slot on the image-receiving element and into the bite of the processing rollers. Thus while the step of manually coupling the two leaders together is eliminated, the photographer must still manually manipulate the coupling tab protruding out of the cassette. Also, the system is capable of only handling one film unit at a time. That is, for each photograph the cassette must be loaded with a single negative sheet element and its corresponding positive sheet must be manually placed in the processor receiving tray.
What is needed is a simplified system where the positive and negative sheet elements may be bulk loaded in appropriate cassette, and/or the processor to eliminate much of the time consuming manual sheet element loading and coupling operations. Also, it is highly desirable to provide a system wherein the coupling tabs or other leader structure do not protrude from the cassette to eliminate the possibility of damage to these tabs and other structure or their interference with the photographic operation.
Self-developing photographic systems wherein discrete negative and positive sheet elements are prepackaged in separate cassettes or are bulk loaded into separate storage chambers of an apparatus and are subsequently brought into superposition for processing are, of course, well known in the photographic art.
For example, U.S. Pat. No. 3,396,646 discloses a camera wherein a pair of feed rollers advance separate positive and negative sheets simultaneously from two separate storage locations into superposed relation and into operative relation with a pressure-applying device. However, the two sheets are not positively coupled together to insure accurate registration. It is obvious that misregistration may occur if there is any slippage at the roller sheet element interfaces.
U.S. Pat. Nos. 2,435,720 and 3,283,684 are representative examples wherein separate positive and negative sheet elements are held in separate cassettes and are subsequently pulled through a pressure-applying device while being brought into face-to-face relation. However, sheet advancement is accomplished by simultaneously pulling on leaders attached to the two sheet elements. By necessity, this design requires that the leaders protrude from the cassettes which is a distinct disadvantage and may result in damage to the leaders or accidental removal of the sheet elements from their respective holding cassettes.
U.S. Pat. Nos. 3,405,617 and 3,405,618 are directed to self-developing photographic apparatus, such as a camera, which holds positive and negative sheet elements provided in separate cassettes. In this design, the cassettes and sheet elements are configured so that leaders or connecting tabs do not protrude from the cassettes prior to the operation of bringing the sheets into superposition for processing. In U.S. Pat. No. 3,405,618, the photosensitive sheet element is exposed and then advanced out of its cassette into a tank holding a liquid processing composition. When the negative sheet element is fully inserted in the tank, its top leader end projects out of the tank in the vicinity of the bite line of a pair of processing rollers. The image-receiving sheet is then advanced from its cassette to a position where its leader end deflects the leader end of the photosensitive sheet element into the bite of the processing rollers which advance the sheets relative thereto to bring them into superposition while applying pressure. In this design, the two sheet elements are not positively coupled together leading to the possibility of misregistration.
The camera disclosed in U.S. Pat. No. 3,405,617 is of similar design, however the leading end of the photosensitive sheet element protruding from the processing tank has a tab receiving slot therein and the leader end of the image-receiving element includes a tapered coupling tab on its leader. When the photosensitive sheet element is fully inserted in the tank, the tab slot in the protruding leader is aligned with the bite line of the pressure applying rollers. The image-receiving sheet is advanced along the path of travel whereby its coupling tab advances through the leader slot and into the bite line of the pressure-applying rollers. Thus the photosensitive and image-receiving sheet elements are positively coupled together to insure accurate registration before the sheets are brought into superposition for processing. However, it should be noted, to effect coupling, the photosensitive sheet element must be completely removed from its holding cassette which requires a substantial number of film handling components to manipulate the two sheet elements in a manner described. Thus, the design suffers somewhat in that it becomes complex mechanically and rather expensive to produce.
Therefore, it is an object of the present invention to provide an easy to use and simple system for operatively coupling together first and second sheet elements of a self-developing film unit; and bringing the sheet elements into superposition for processing the same.
It is yet another object of the invention to provide a photographic apparatus wherein at least one of the sheet elements is held in a cassette supported on the apparatus and having an access opening therein and the apparatus includes sheet advancing means for advancing the second sheet element of a film unit through the access opening whereupon it automatically becomes coupled with the first sheet element therein.
It is yet another object to provide such a photographic apparatus wherein a portion of the leader of one of the two sheet elements is automatically advanced through a withdrawal opening in the cassette and located at a position where it may be engaged, for example by a pair of pressure-applying rollers, for automatically advancing the first and second coupled sheet elements from the cassette to bring them into superposition for processing.
It is yet another object of the invention to provide such an apparatus and cassette wherein the cassette is configured to hold a stack of sheet elements therein so the coupling means or the leaders on the sheet elements held in the cassette do not protrude therefrom during normal handling and manipulative operations so that these leaders are protected from damage prior to sheet advancement from the cassette for processing operations.